218 
AUG. F. FOERSTE 
dorsal. A vertical dorsoventral section through the center of 
the specimen exposes two septa, of which the lower is more dis- 
tinct. This septum rises from a level of 6 mm. above the base 
of the specimen on its ventral side to 17 mm. at a point 4.5 mm. 
distant from its dorsal wall. The upper septum is 4 mm. above 
the first on its ventral side and rises to 25 mm. above the base of 
the specimen at a point 1.5 mm. from its dorsal wall. The dorsal 
terminations of these septa are unknown ; no trace of the 
siphuncle remains. 
The lateral view reproduced as figure 2A, Plate XXXV, shows 
the ventral side on the left. Figure 2B on the same plate presents 
the ventral side, and figure 2C the dorsal. 
Locality : From the Catheys formation at Williamsport, Tenn- 
essee. Specimen 48395 in the U. S. National Museum. 
Remarks : This species may be a precursor of typical Billing- 
sites, the rise of the septa on its dorsal side forshadowing the 
formation of the strongly developed dorsal saddles of that genus. 
18. ORTHOCERAS BREYNIUS 
The name Orthoceras or Ortho ceratites was applied first by 
Breynius““ to erratic specimens found in the vicinity of Danzig 
in Germany. From this location it may be assumed that the 
erratic blocks containing these specimens were either of Ordovi- 
cian or Silurian origin. There is a possibility that some one 
visiting the original locality might be able to identify the species 
figured. Nothing is known as to the fate of the original speci- 
mens. 
The figures published by Breynius show that the rate of en- 
largement of the species described by him was very small. The 
septa were relatively distant, about 2 camerae occurring in a 
length equal to the diameter of the conch. The siphuncle was 
small, omewhere between one-sixth and one-seventh of the 
diameter of the conch. Its segments were cylindrical, not en- 
larging within the camerae. The septa were deeply concave. 
The nearest approach to Orthoceras, as figured by Breynius, 
with which the writer is familiar, is a species of Lituites, from 
Esthonia, well represented in the collection of the U. S. National 
Museum (Plate XXVIII, Fig. 3). In these specimens the an- 
nulations on the exterior of the shell are accompanied by very 
weak annulations on casts of the interior. The camerae of this 
“ Dissert. Phys. de Polythalmiis, 1732, pp. 12, 19, 31; PI. Ill, Figs. 1-7. 
